Volcano

This lands enters the battlefield tapped.
{t}: Remove all counters on this land and get that
much red manas.
At the end of your turn, put a counter on this
land.
If there are eight or more counters on this land, sacrifice it. It deals 6 damage damage to all
players and creatures. Each player sacrifices six permanents they control. Then, search your
library for a mountain and put it onto the battlefield tapped.